Association between Systemic Inflammatory Markers Based on Blood Cells and Polysomnographic Factors in Obstructive Sleep Apnea

Objectives

Systemic inflammation plays a key role in the pathogenesis of obstructive sleep apnea (OSA); however, methods to easily evaluate the severity of systemic inflammation are yet to be developed. This study aimed to analyze the association between systemic inflammation markers, which could be derived from the complete blood count (CBC) profile, and sleep parameters in a large number of patients with OSA.

Methods

Patients who visited our hospital's Otorhinolaryngology Sleep Clinic between January 2017 and February 2022 underwent polysomnography and routine laboratory tests, including CBC. Associations between three systemic inflammatory markers, systemic immune-inflammation index (SII), neutrophil-lymphocyte ratio (NLR), and platelet-lymphocyte ratio (PLR), and polysomnographic and demographic factors including age, sex, body mass index, apnea-hypopnea index (AHI), hypopnea index (HI), lowest oxygen saturation (%), Pittsburgh Sleep Quality Index (PSQI), Epworth Sleepiness Scale, and percentages of non-Rapid Eye Movement (REM) sleep stage 3, REM sleep, and snoring time were analyzed. The inflammation markers of different OSA subgroups were also compared. The association was also analyzed in subgroups with different OSA severities.

Results

A total of 1102 (984 male, 134 female) patients were included, and their mean age was 46.70 ± 13.15 + mean AHI. PSQI (p = 0.027) was significantly associated with SII. There were no significant independent factors for the NLR and PLR. Within the simple snorer and mild OSA subgroups, there was no significant association between sleep parameters and the SII. In the severe OSA subgroup, AHI (p=0.004) and PSQI (p=0.012) were independently associated with SII.

Conclusion

Our study analyzed systemic inflammatory markers based on a simple, relatively cost-effective test, complete blood count, and showed that AHI and SII were significantly correlated only in the severe OSA subgroup.

A Randomized Controlled Trial of Sleep Study Surveillance with Targeted APAP Therapy for Obstructive Sleep Apnea in Pregnancy

OBJECTIVE(S)

To determine effects of targeted autoregulated positive airway pressure (APAP) in women at risk for obstructive sleep apnea (OSA) on adverse pregnancy outcomes (APOs), cost, and natural history of OSA.

STUDY DESIGN

Pregnant women at high risk for OSA were randomized to a sleep study screening group with possible initiation of APAP compared to women not screened for OSA, receiving standard obstetric care (control). Women in the sleep study screened group received a sleep study at two points during pregnancy, early (6-16 weeks) and late (27-33 weeks), with initiation of APAP therapy if their apnea hypopnea index (AHI) indicated ≥ 5 events per hour. Women of both groups had a sleep study 3 months postpartum. The primary outcome was effect on APO, a composite of hypertension, preterm birth, low birthweight, stillbirth and diabetes. Secondary outcomes included OSA severity and hospital costs.

RESULTS

Among 193 women randomized (100 sleep study screened group; 93 control group; 6 lost to follow up), there were no significant differences in composite APO (46.4% screened vs. 43.3% control, p=0.77), hypertension (23.7% screened vs. 32% control, p=0.25), preterm birth (13.4% screened vs. 10% control, p=0.5), low birthweight (5.2% screened vs. 6.7% control, p=0.76), stillbirth (1% screened vs. 0% control, p=1), gestational diabetes (19.6% screened vs. 13.3% control, p=0.33), or mean cost ($12,185 screened vs. $12,607 control). The AHI increased over the course of pregnancy, peaking at 3 months postpartum (p<.001). There were 24 (25.8%) subjects who had a new diagnosis of OSA, with 6 in whom APAP was prescribed. APAP compliance rates were poor with usage rates ranging from 2% (1 of 64 days) to 43% (6 of 14 days).

CONCLUSION

Targeted APAP therapy for OSA in a sleep study screened high risk pregnancy group did not decrease composite adverse pregnancy outcomes or hospital costs compared to a group that received no OSA screening. However, a small sample size, low APAP prescription rates and poor compliance resulted in difficulty in drawing a definitive conclusion. The prevalence and severity of OSA worsened over the course of pregnancy, with the highest rates detected in the postpartum period. Large, multi-center clinical trials that are adequately powered are needed.

Assessment of the relationship between endocan and obstructive sleep apnea severity

INTRODUCTION

Obstructive sleep apnea (OSA) and endothelial dysfunction are associated with cardiovascular risk factors and the development of atherosclerosis. Endocan is a marker of endothelial dysfunction, while obstructive sleep apnea is one of the causes of endothelial dysfunction. In this study, we investigated the relationship between endocan and obstructive sleep apnea severity.

MATERIAL AND METHODS

A total of 179 patients with snoring complaints were included. All patients underwent polysomnography, and based on the results, the participations were allocated to the control group (n = 39) or to the obstructive sleep apnea group (n = 140). The OSA group was classified as having mild (apnea-hypopnea index (AHI) = 5-15; n = 43), moderate (AHI = 15-30; n = 42), or severe OSA (AHI > 30; n = 55). All participations had their endocan levels measured.

RESULTS

Endocan levels in OSA patients were significantly higher than in the control group (11.8 (3.13-200) vs 3.13 (3.13-23) ng/ml, p < 0.001). Also, endocan levels were significantly higher in the severe OSA group than moderate and mild obstructive OSA (13.2 (3.13-200), 12.6 (3.13-200) and 8.44 (3.13-50.5) ng/ml, p = 0.015, respectively). Multiple logistic regression analysis showed that smoking, age and endocan levels were independent predictors of OSA severity (p = 0.024, p = 0.037, p = 0.004, respectively).

CONCLUSIONS

Endocan seems to be a potential risk stratification marker in this patient population.

Expiratory Time Constant and Sleep Apnea Severity in the Overlap Syndrome

STUDY OBJECTIVES

Lung mechanics in the overlap of COPD and sleep apnea impact the severity of sleep apnea. Specifically, increased lung compliance with hyperinflation protects against sleep apnea, whereas increased airway resistance worsens sleep apnea. We sought to assess whether the expiratory time constant, which reflects lung mechanics, is associated with sleep apnea severity in such patients.

METHODS

Polysomnographies in 34 subjects with the overlap syndrome were reviewed. Three time constants were measured for each of up to 5 stages (wake, NREM stages, and REM). The time constants were derived by fitting time and pressure coordinates on the expiratory portion of a nasal pressure signal along an exponentially decaying equation, and solving for the time constant. Demographics, morphometrics, wake end-tidal CO2, right diaphragmatic arc on a chest radiograph, and the apnea-hypopnea index (AHI) were recorded.

RESULTS

The time constant was not associated with age, gender, body mass index, right diaphragmatic arc, or wake end-tidal CO2, and was not significantly different between sleep stages. A mean time constant (TC) was therefore obtained. Subjects with a TC > 0.5 seconds had a greater AHI than those with a TC ≤ 0.5 seconds (median AHI 58 vs. 18, respectively, p = 0.003; Odds ratio of severe sleep apnea 10.6, 95% CI 3.9-51.1, p = 0.005).

CONCLUSIONS

A larger time constant in the overlap syndrome is associated with increased odds of severe sleep apnea, suggesting a greater importance of airway resistance relative to lung compliance in sleep apnea causation in these subjects.